Improvement in hot-air engines



G. CRANE. HOT AIR ENGINE.

Patented Jan; 81 1865.

To all whom it may concern.-

' UNITED STATES PATENT OFFICE.

MOSES c. Genus, or CHELSEA, MASSACHUSETTS.

IMPROVEMENT IN HOT-AIR ENGINES.

Specification forming part of Letters Patent No. 46,084, dated January31, 1865.

clare that the following, taken in connectionwith the drawings, whichaccompany and form part of this specification, is a description'of myinvention'suflicient to-enable those skilled in the art to practice it.p

Of said drawings, Figure l.shows my improved hot-air engine inperspective with some of the parts broken away to exhibit internalstructure. Fig. 2 is a vertical section taken through one of theair-pumps and the furnace therewith connected,

A represents the bed of the engine, and B the main or working cylinderthereof, which is provided with heads and a suitably-packed piston,similar. to an ordinary steam-engine cylinder.

The piston-rod, cross-head, slides, crank, connecting-rod,balance-wheel, shaft, and upright supports usual for ordinary verticalengines are all plainly shown in the drawings and need not be referredto by letters.

Two air-pumps, O G, are shown, each connected, respectively, with itsown air-heating furnace D and D. From one of these pumps, 0, air issupplied to the maincylinder B above its piston to drive it downward,while from the other pump, 0, air is supplied to the main cylinder belowthe piston to drive it upward. The air-pumps C and O and also thefurnaces D and l) are similar in construction and operation. The pump 0is provided with a piston, G, which is operated through its pistonrod 0by the following 01' other mechanical devices, which operate to drivedown the airpump piston faster than the piston moves in cams being alsoso fashioned as to cause the pump pistons to rest at the completion oftheir downward stroke till the engine-piston completes the stroke whichis made by the expansion of the air supplied :by one or the other of thepumps, and said cams being also further. fashioned so that the upwardstroke of the pump-pistons shall be coincident, or nearly so,

with the strokes forthe engine-piston.

The particular mechanism shown in the drawings for efiecting thedili'e'rent velocities of motion between the piston in. theenginecylinder and the pistons in the air-pumps consists of a crank,1",011 the engine-shaft, having its crank-pin it working in the slot fof one bars, as shown in Fig. 2, or the air-passage may be so made as todeliver the air partly above the grates, if desired. The air in passingfrom the furnaces into the main cylinder enters the pump-barrels throughpipes K K, above thepump-pistons, before passing into one or the otherend of the engine-cylinder, so that' during .the downward stroke of thepump-pistons the pressure is alike on both sides.

From the pipes L and L, which form the air-passages between the maincylinder and the pump'barrels, the exhaust-pipes M and M rise from themain oylinder'B, each being provided with an exhaust-valve so operatedby mechanism as to be opened and closed at the times needed for theperfect working 0t,the engine. This mechanism is as follows: Passingthrough each exhaust'pipe is a crankedshaft, 3 and in the pipes M and M,respectively, and on said shaft 3 are valves m and m, by which theexhaust-passages can be left open to the atmosphere or by which they maybe wholly closed. In each lever H Hflare tappet-eyes a a, through whichrods n n can freely work, each having a stop on its upper small portionof the first of its stroke, said end, so that when by the movement of HH The other arm of the bent the tappets strike the stops on n 12, oneexhaustvalve is closed and the other is opened, thisbeing effected bythe partial rotation or rock:

ing of the cranked shaft y, caused by the conwell-'as-iwith one end of'the main cylinder B,

Whenth'e pump pistons are rising, and it will therefore appear that inthe upward movement ofthe'pump-pistons, as well as in their downwardmovement, the pressure on each side thereof is a1ike. From this itfollows that by the construction or arrangement shown by which theair-pump pistons work in equilibrium, substantially as shown, and inwhich arrangement my invention principally consists, no power isrequired to work the pumps other than that which is absorbed in frictionof the machinery and of the air in'the passages, the operation of thepumps being to displace cold air from a cool place and to cause it toflow-through the furnace, where it is heated and expanded, the pressureon both sides of each pumppiston in this operation-being alike.

In the pipes which connect the pumps at their bases with the furnaces, Iplace regula- -t0r-valves p, to be operated upon by any wellkuown formof governor worked by the engine. In the piston of the air-pinup Iarrange a 'valflylike that marked 0, to be kept shut by its weight or bya spring, and intended to operate so as'tolet the'piston pass the'airbeneath it when the regulator works the valve p to prevent or check theair from passing through the furnace to be heated.

I claim- 1. In hot-air engines, the. arrangement of the main cylinder,the ainpump, the furnace, the air-passages, and exhaust-valve, so thatthe air-pump piston shall work with equal pressare on each side thereof,substantially as set forth.

said piston completes its said stroke before.

the main cylindenpiston completes the stroke which is consequent uponsaid supply.

In witness whereof {have hereunto set my hand this. 3d day of December,A. I). 1864.

Moses e. CRANE.

In presence nf-' J. B. CnosnY, FRANCIS GOULD.

